Would a physical change be separating an oil from solution by cooling it?

The other options are:
Creating salt by reacting sodium metal and chlorine gas.

Allowing a nail to rust.

Building a model rocket propelled by mixing baking soda and vinegar.

Question

Would a physical change be separating an oil from solution by cooling it? 

The other options are:
Creating salt by reacting sodium metal and chlorine gas.

Allowing a nail to rust.

Building a model rocket propelled by mixing baking soda and vinegar.

anonymous · Answer

@aaronq

aaronq · Answer

A chemical reaction is that where bonds are broken and new bonds are formed. The separation of substances by manipulating their melting points is physical, no bonds are broken, only a change of state occurred.

preetha · Answer

Ask yourself, has the chemical identity of anything changed because of the process?  If not, it is possibly a physical change.

anonymous · Answer

Well, allowing a nail to rust would change it's physical properties, right?

aaronq · Answer

It's chemical, Iron (Fe) is oxidized by oxygen into iron oxides (e.g. $Fe_2O_3$), which would be categorized as a redox reaction.

preetha · Answer

Good job Aaron.

aaronq · Answer

Thanks, Dr. Preetha.

anonymous · Answer

I am still unsure of the correct answer..

abb0t · Answer

Well, what do you think it is, based on the explanations given by the users above? Which btw, have given great explanations :-)

anonymous · Answer

Well I believe it is separating an oil from solution by cooling it. @abb0t

aaronq · Answer

That is the answer.

anonymous · Answer

Thank you, @aaronq , another medal for you :)

aaronq · Answer

lol thanks!